A disk recording and reproducing apparatus (disk apparatus) such as hard disk drive (HDD) is designed to record and reproduce data on a recording surface of a disk as recording medium by means of a head. The HDD has a head support device (also known as head actuator device or carriage device), and the head is supported by it in a floating state with a specified interval above the disk recording surface, and is designed to move in the radial direction above the disk, and such configuration and construction are proposed in various publications (for example, see page 4 of Japanese Patent Laid-open Application No. H9-82052).
As an example of head support device of a conventional disk apparatus having a floating type head, a head support device in a magnetic recording and reproducing apparatus such as HDD is explained by referring to FIG. 19 which is a plan view of structure of essential parts of magnetic recording and reproducing apparatus, and FIG. 20 which is an essential perspective view explaining the structure and action of head support device.
In FIG. 19, a head support device 101 comprises a load beam 102 of relatively low rigidity, an elastic member 103, and a carriage 104 of relatively high rigidity, and a slider 105 mounting a magnetic head (not shown) is provided beneath an end of the load beam 102.
A magnetic recording medium 106 is designed too be rotated by a spindle motor 107, and at the time of recording or reproduction of the magnetic recording and reproducing apparatus, the slider 105 is lifted from the magnetic recording medium 106 by a specified amount, owing to the balancing relation between the buoyancy the slider 105 receives by the air stream generated by rotation of the magnetic recording medium 106 and the thrusting force of the elastic member 103 of the head support device 101 for forcing the slider 105 toward the side of the magnetic recording medium 106, that is, the magnetic head mounted on the slider 105 is lifted from the magnetic recording medium 106 by a specified amount.
At the time of recording or reproduction of the magnetic recording and reproducing apparatus, the head support device 101 is rotated about a second bearing 109 by the action of a voice coil 108 provided at the opposite side of the load beam 102 of the carriage 104, and the magnetic head mounted on the slider 105 is positioned against a desired track of the magnetic recording medium 106, thereby performing recording or reproduction.
Referring further to FIG. 20, the structure and action of the head support device 101 are explained. FIG. 20 is an essential perspective view of the section of the magnetic head in the head support device 101 in FIG. 19.
In FIG. 20, the magnetic head (not shown) is provided at the opposite side of the magnetic recording medium (not shown) of the slider 105 provided at the lower side of one end of the load beam 102. Other end of the load beam 102 is folded, and an elastic member 103 is formed, and the elastic member 103 is stopped at the carriage 104. To suppress changes of load of the slider 105 on the magnetic recording medium due to surface deflection or perpendicular motion of the magnetic recording medium, or manufacturing fluctuations in the distance between the slider 105 and magnetic recording medium at the time of mass production, a notch 111 is provided in the elastic member 103, and the rigidity of the elastic member 103 is lowered, and the spring constant is decreased so as to have a sufficient flexibility.
Besides, torsion and other changes of the carriage and others are also known to have a serious effect on the operation of the head support device, and technologies for decreasing the vibration mode such as distortion have been proposed (for example, see page 6 of Japanese Patent Laid-open Application No. H8-45214). In such specific proposal, by adjusting the bent shape of the spring section (corresponding to the elastic member), and optimally setting the bump (corresponding to the bending size of the spring section) and offset (corresponding to the difference in position height between the connecting portion of the load beam and spring and the portion of connecting the spring section to the carriage), the slider is hardly moved despite linear torsional resonance frequency.
In the head support device of such conventional structure, however, since it is designed to lower the rigidity of the elastic member 103, decrease the spring constant and hence obtain a sufficient flexibility by providing the notch 111 in the elastic member 103 or forming the load beam 102 in a thin plate structure, the resonance frequency declines when the head support device 101 moves the magnetic head to a desired track position at high speed, and vibration mode such as torsion occurs, and consequently off-track may occur, it may take a longer time to settle the vibration mode, and there is a limit for shortening the access time.
Besides, if the bump and offset are set optimally by adjusting the bending shape of the spring section, although it is effective for the linear torsional resonance frequency, enough effect is not obtained for higher torsional resonance frequency. Optimal setting of the bump and offset in the spring section requires adjustment in each head support device in consideration of manufacturing fluctuations of distance between the head arm (corresponding to the carriage) and the disk, and this is not an easy operation, and the number of manufacturing processes is increased.
The speed of moving the magnetic head to a desired track position is becoming faster recently, and hence a very high torsional vibration frequency is provided as torsional vibration mode, and the magnetic head may go off the desired track position owing to the higher torsional vibration mode.
To make the linear torsional mode of the load beam less obvious, the bending shape of the spring section (elastic member) of the load beam is adjusted. However, when the setting height (Z-height) of the load beam is changed, the characteristic is changed, and extra adjustment is needed to obtain a stable performance.
It is hence an object of the invention to solve these problems and present a head support device which is free from effects of manufacturing fluctuations of the distance between the carriage and magnetic recording medium, heightened in rigidity of load beam to have a very large resonance frequency, free from effects of fluctuations of setting height of load beam, stabilized in resonance characteristic, enhanced in the reliability of head positioning control characteristic so as to be free from off-track problem against higher torsional resonance, small in size and light in weight, and excellent in operation stability, and a disk apparatus having such head support device.